Sheet metal forming apparatus

ABSTRACT

A sheet metal forming apparatus comprising an upstanding member having a pressure foot on the upper end thereof movable into a work clamping position. A rotatable forming member engages the free edge of the workpiece and reversely bends it about a lip formation provided on the pressure foot. Prior to the completion of the bending operation, the pressure foot is pivotally withdrawn from the workpiece to permit the forming member to overbend the reversely bent portion of the workpiece beyond 180* and permit the natural resiliency of the material to restore the reversely bent portion to a true 180* reverse bend.

United States Patent Jones, Jr. et al.

1151 3,662,584 14 1 May 16,1972

[54] SHEET METAL FORMING APPARATUS Niagara Machine 81'. Tool Works, Buffalo, NY.

[22] Filed: June 15, 1970 [21] Appl.No.: 46,102

[73] Assignee:

1,530,502 3/1925 Lange ..72/32l FOREIGN PATENTS OR APPLICATIONS 6,629 7/1909 Great Britain ..72/702 Primary ExaminerCharles W. Lanham Assistant Examiner-Michael J. Keenan Attorney-Christel & Bean ABSTRACT [52] U.S. Cl ..72/41l, 72/321 A s e me al forming apparatus comprising an upstanding 511 1111.01 ..B21d 31/00 member h ng a pr ssure foot on the u er end thereof 58 Field of Search ..72 41 1, 310, 319, 320, 321, movable into a work amp ng ositi n. A rotatable forming 72 322 member engages the free edge of the workpiece and reversely bends it about a lip formation provided on the pressure foot. 56] References Cited Prior to the completion of the bending operation, the pressure foot is pivotally withdrawn from the workpiece to permit the UNITED STATES PATENTS forming member to overbend the reversely bent portion of the workpiece beyond 180 and permit the natural resiliency of 1,192,797 7/1916 Salmon, Jr ..72 32() the material to restore the reversely bent portion to a true 2,028,869 1/1936 Jensen ....72/3l9 reverse bend. 2,687,162 8/1954 Smlth ....72/32l 2,394,193 2/1946 McCabe ..72/321 7 Claims, 8 Drawing Figures 92 82 J W 74 96 Q 1 47% I M g 132 I l2 e7 66 8 58 P06 54 I 1 1 n I I 1 I." 513 I I i110 -*-1 i I34 1' H2 I36 1 I40 I I0 1 PATENTEUMAY 16 I372 SHEET 1 BF 4 FIG..L

" INVENTOR.

CLARENCE O. JONES .JR.

F. SNUSZKI FQED ATTOQN EVS PATENTEDM I I912 3.662.584

sum 3 OF 4 INVENTOR.

CLARENCE O. JONES. JR. Bul -QED F. SNUSZK\ wvm ATTOQNEYS PATENTEDMAY 16 I972 3,662,584

sum u UF 4 FIG.4. I H66 INVENTOR. CLARENCE O. JONES JQ.

ii RED F. SNUSZK! B ATTOQNEYS.

SHEET METAL FORMING APPARATUS BACKGROUND OF THE INVENTION The present invention relates to an apparatus for forming sheet metal and, more particularly, to an apparatus for forming cleats or reversely bent formations along the edge of a sheet of metal in a single operation, the reversely bent portion being parallel to but spaced slightly from the body of the sheet.

In various heating, cooling or ventilating systems it is common to employ a series of square or rectangular shaped conduits connected in an end to end relation to form a substantially continuous duct system. In forming these conduits, a pair of blanks of rectangular shape are provided with V-shaped notches at their opposite ends and flanges or locking seams along their longitudinal edges. The blanks are then bent or folded along longitudinal axes extending between the notches into rectangularly shaped sections which are mated and interlocked together along their longitudinal seamed edges to form a closed box-like conduit.

In order to secure these finished conduits together in end to end relation, cleats or reversely bent portions are formed at the opposite ends of such conduits so that adjacent sections may be joined together by conventional S-cleats. These reversely bent portions are generally formed on the opposite ends of the flat blank prior to folding it into a right angular shape. It is important that the reversely bent portion be disposed parallel to the plane of the blank to insure a proper interlocking fit of the conduits in the assembled relation, the reversely bent portion being spaced approximately a metal thickness from the body of the sheet.

Various machines for forming these cleats or reversely bent portions along the opposite edges of a flat blank are known. The problem of attaining the desired degree of reverse bending is complicated when the return bent flange must lie fairly close to the main body of the sheet. Prior machines for forming return bends of this nature generally require two bending devices and two separate bending operations. Initially, the edge of the metal sheet is partially return bent about an anvil or forming member. After the first forming member disengages the work, the partially return bent portion is introduced to a second machine or second forming station which completes the return bending operation.

SUMMARY OF THE INVENTION The sheet metal forming apparatus of the present invention, as hereinafter described, obviates the above disadvantages by providing a movable pressure foot and a rotatable forming member operable in conjunction to form a true 180 reverse bend along the edge of a metal sheet in one operation, thereby eliminating a series of machines, multiple setting-up operations, and multiple handling of the workpieces, and thereby realize a substantial savings in cost.

Generally speaking, the sheet metal forming apparatus of the present invention comprises a pressure foot movable vertically for clamping a workpiece between the pressure foot and a hold-down bar. The pressure foot is provided with a lip formation about which the edge of the workpiece is bent. A rotatable forming member engages the free edge of the workpiece and bends it about the lip formation. Just prior to the completion of the bending operation, the pressure foot is withdrawn and disengaged from the workpiece to permit the forming member to overbend the reversely bent portion of the workpiece beyond 180. The forming member is then reversely rotated allowing the natural resiliency of the reversely bent portion to spring the same back into the desired orientation, usually parallel to the plane of the workpiece.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. I is a side elevational view of one form of sheet metal forming apparatus constructed in accordance with the present invention;

FIG. 2 is a front elevational view, partially broken away and in section to more clearly show details of the apparatus of FIG. 1;

FIG. 3 is a vertical sectional view taken on line 33 of FIG.

FIG. 4 is a vertical sectional view taken on the line 4-4 of FIG. 2;

FIG. 5 is a vertical sectional view taken on the line 5-5 of FIG. 2; g

FIG. 6 is a fragmentary vertical sectional view showing the clamping members and forming members in position just prior to the bending operation;

FIG. 7 is a view similar to FIG. 6 showing the relative position of the parts during the bending operation; and

FIG. is a view similar to FIG. 6 illustrating the relative position of the parts upon completion of the bending operation.

DESCRIPTION OF THE PREFERRED EMBODIMENT Referring now to the drawings in detail, there is shown in FIG. 1 a sheet metal forming apparatus, generally designated 10, constructed in accordance with this invention and comprising a frame 12 which may be suitably mounted on a support base (not shown). The apparatus 10 is preferably positioned adjacent a conveyor mechanism, shown schematically in FIG. 3 and identified by the reference character 14, which conveyor mechanism may be of any conventional type for feeding blank workpieces to the apparatus 10 and to remove finished workpieces therefrom. Frame 12 comprises a pair of side walls 16 (FIGS. 2 and 3), a bottom wall 18, a top wall 20 and an upper front wall 22 welded or otherwise fixedly secured together to form an integral machine frame structure. A pair of end caps 23 having slotted openings 24 therein are mounted in side walls 16, the openings 24 adapted to receive one end of a workpiece W in the form of an elongated metal sheet, as will hereinafter become apparent.

As'shown in FIG. 2, a horizontally extending crankshaft 26 extends across frame 12 and is joumalled for rotation in suitable bearings 28 mounted in the opposite side walls 16 of frame 12. Crankshaft 26 also is joumalled for rotation in spaced bearing blocks 29 mounted on the bottom wall 18 of frame 12. In the form of the invention illustrated herein, the drive means for crankshaft 26 is disposed exteriorly of one side wall 16 and comprises an electric driving motor 30 having an output shaft 32 on which is mounted a drive pulley 34. An endless drive belt 36 is trained about pulley 34 and-a flywheel 38 mounted on a shaft 40. The shaft 40 is operatively connected to the crankshaft 26 through a clutch-brake assembly 44 and a gear reduction mechanism 46. A belt guard 48 is suitably mounted on frame 12 and shrouds drive pulley 34, belt 36 and flywheel 38 for protecting the same.

Rigidly mounted on crankshaft 26 adjacent opposite ends thereof are a pair of cams 50 engageable with cam followers 52 carried by a pair of rocker arms 54. Each rocker arm 54 is provided with an angle member 56 having one leg secured to the underside of rocker arm 54 by suitable fasteners 58. The other leg of angle member 56 extends downwardly and is provided with a suitable opening for receiving the threaded shaft 60 of follower 52. A suitable nut 62 is threaded onto shaft 60 for securing follower 52 in place. The rearward end of each rocker arm 54 is pivotally mounted on a cross shaft 64 extending between side walls 16. The forward end of each rocker arm 54 is suitably mounted on a pin 66 extending between a pair of spaced lugs 67 projecting rearwardly from an upright member or bedplate 68. Thus, the rotational movement of crankshaft 26 is translated into vertical reciprocating movement of bedplate 68 through cams 50 and rocker arms 54.

A pressure foot 70 is secured to the upper end of bedplate 68 by means of suitable fasteners 72 spaced longitudinally along pressure foot 70. Pressure foot 70 is provided with a generally horizontal, planar top surface 74 and a lower inclined surface 76 which extends upwardly from bedplate 68 at an angle toward surface 74 to form a lip formation 78 about which the metal is bent as will hereinafter be explained.

An elongated hold-down bar or clamping member 80, extending crosswise between side walls 16, is secured to the lower end of the upper front wall 22 of frame 12 and is provided with a series of spaced, work engaging projections 82 extending downwardly from the inner end of member 80 as shown in FIG. 3. The workpiece W is clamped between the projections 82 and the inner end of surface 74 of pressure foot 70 when in its raised position for firmly securing the workpiece to be formed. The spaces defined between projections 82 accommodate the locking seams previously formed along the longitudinal edges of workpieces W of varying widths.

A rotatable bending segment 84 extends crosswise of frame 12between the side walls 16 and is provided with rollers 86 (FIG. 2) at the opposite ends thereof guided for'movement in arcuate grooves or tracks 88 provided on the inner surfaces of end caps 23. Segment 84 is provided with an arcuate peripheral surface 90 and a flat inner surface 92 having a folding or bending shoe 94 rigidly secured thereto as by means of fasteners 96. Shoe 94 is rotatable along with segment 84 and has a work'contacting surface 96 for engaging and reverse bending the marginal edge of a workpiece W about lip formation 78. A portion of segment 84 intermediate the opposite ends thereof is provided with gear teeth 100 for a purpose presently described.

The means for rotating segment 84 includes the crankshaft 26 which is provided with crank 102 having a pin 104 for mounting a connecting rod 106 thereon. Rod 106 has a rounded, bifurcated, semi-circular bearing portion 108 engageable partially about pin 104 and secured to a bearing cap 110 by fasteners 112. The other end of rod 106 is eccentrically connected to a gear 116 by means of a crank pin 117. The gear 116 is rotatably mounted on a stub shaft 120 projecting laterally from a plate member 122 depending from the top wall of frame 12. As crankshaft 26 rotates 360, connecting rod 120 is caused to reciprocate to in turn effect reciprocating rotational movement of gear 1 16.

Gear 116 meshes with a pair of idler gears 126 and 128 suitably journalled for rotation on stub shafts 130 and 132 mounted on frame 12. The idler gears 126 and 128 are adapted to mesh with the gear teeth 100 on segment 84. Initially, only gear 126 meshes with teeth 100 to rotate segment 84 in a clockwise direction as viewed in FIG. 3.

After segment 84 has been partially rotated, the teeth 100 engage gear 128 so that during a portion of the rotational movement of segment 84, both idler gears 126 and 128 mesh with teeth 100. Upon final rotation of segment 84, only gear 128 is effective to complete the rotational movement of segment 84.

Pressure foot 70 also is adapted to be tilted or pivoted out of its work engaging position into the position shown in FIG. 8 in order to permit shoe 94 to complete the bending operation. To this end. the lower portion of bedplate 68 is provided with a pair of spaced brackets 134 extending inwardly from the inner surface of bedplate 68. Brackets 134 are provided with cam followers in the form of rollers 136 guided for movement in cam cracks 138 provided on a pair of spaced cams 140 rigidly secured to crankshaft 26. As shown in FIG. 5, each cam track 138 has a retreating portion 142 so that when followers 136 enter portions 142 during the rotation of cams 140, the brackets 134 are moved inwardly toward crankshaft 26 to pivot bedplate 68 about a pivot axis defined by pins 66 in a counterclockwise direction as viewed in FIG. 3, causing pres sure foot 70 to be rocked or tilted out of engagement with the workpiece W and allowing shoe 94 to be further rotated to overbend the reversely bent portion of the workpiece edge.

In operation, a workpiece W is brought into the position shown in FIG. 3 with the end to be worked accurately positioned between clamping member 80 and pressure foot 70. The main body portion of the workpiece W rests on a worktable or conveyor 14 and may be manually positioned or automatically positioned by means of guides and stops (not shown) in an automated system. The free edge of workpiece W projects beyond the hold down projections 82. As crankshaft 26 rotates by means of motor 30 and the drive train hereinbefore described, the rocker arm followers 52 engage the high portions of cams 50 to raise the bedplate 68 and thereby pressure foot 70 upwardly against the lower surface of the workpiece W to clamp the same between the foot 70 and hold-down projections 82 as shown in FIG. 6.

Further rotation of crankshaft 26 effects reciprocating movement of the connecting rod 106 to effect partial rotation of disc 116 in a clockwise direction as viewed in FIG. 3 to rotate idler gear 126 in a counterclockwise direction. The teeth of gear 126 meshing with the teeth of segment 84 rotates the same in a clockwise direction causing shoe 94 to engage the upper surface of the protruding edge of workpiece W and reversely bend the same about lip formation 78, During the rotational movement of segment 84, gear 128 engages with the teeth 100 of segment 84 and facilitates rotational movement of the latter.

As the reversely bent portion of the workpiece W engages the lower inclined surface 76 of pressure foot 70 as shown in FIG. 7, cam follower rollers 136 enter into the retreating portions 142 of cam tracks 138 to tilt bedplate 68 about pivot pins 66 in a counterclockwise direction as viewed in FIG. 3 to thereby move pressure foot 70 out of engagement with the workpiece W as shown in FIG. 8.

Further rotation of segment 84, solely under the influence of idler gear 128, effects an overbend in the reversely bent portion of the workpiece beyond as shown in FIG. 8. As the crankshaft 26 continues to rotate, the hereindescribed movements of the various parts are reversed to restore the bedplate 68 and the bending head to their original positions as shown in FIG. 3 in readiness for the next cycle of operation. Upon disengagement of shoe 94 from the workpiece W, the reversely bent portion thereof springs back into the desired orientation whereby such portion is parallel to but spaced from the plane of the metal sheet. This cycle is repeated for each 360 of rotation of crankshaft 26. This operation can be manually controlled by means of a suitable on-off switch (not shown) or automatically cycled by means of a suitable control means (not shown) incorporating the usual stop limit switches, relays, and timing mechanisms for removing a finished workpiece by suitable conveyor means and'presenting a properly positioned fresh blank to the apparatus 10.

The present invention thus provides an improved sheet metal bending apparatus which is simple and strong in com struction, rugged and durable in use, and which forms a true 180 reverse bend along the edge of the workpiece in a single operation. By the provision of a tiltable pressure foot about which the metal is bent and which is moved out of the way after partial bending of the work, the work engaging shoe can be rotated sufficiently to produce a slight overbend so that the natural springback inherent in the metal restores the bent portion to its desired orientation. If desired, both ends of the workpiece can be simultaneously bent by providing a pair of metal forming machines of this invention in a spaced, opposed relation.

An illustrative embodiment of this invention having been herein described and illustrated in the drawings, it is to be understood that numerous modifications thereof can be made without departing from the spirit and scope of this invention.

We claim:

1. Apparatus for forming a reverse bend along an edge of a sheet of metal comprising: a frame, a pressure foot mounted on said frame and having a lip formation along an edge thereof, a stationary clamping member mounted on said frame above said pressure foot, means for raising said pressure foot for clamping a workpiece between said clamping member and said pressure foot with the marginal edge of said workpiece protruding beyond said clamping member and said pressure foot, means engageable with said marginal edge of said workpiece for reversely bending said marginal edge about saidlip formation, means for withdrawing said pressure foot from said workpiece to disengage said lip formation from said workpiece while said bending means is maintained engaged with said marginal edge for continued bending thereof, means operable subsequent to said disengagement for continuing the movement of said bending means to continue reverse bending to the degree required to compensate for springback and produce a final reverse bend of the required degree.

2. Apparatus according to claim 1 wherein said means for raising said pressure foot comprises a rotatable shaft, a cam mounted on said shaft, a rocker arm connected at one end to said pressure foot and having a cam follower engageable with said cam, the other end of said rocker arm being pivotally mounted on said frame.

3. Apparatus according to claim 1 wherein said means for withdrawing said pressure foot from said workpiece comprises a rotatable shaft, a cam mounted on said shaft, a bracket connected to said pressure foot and having a cam follower engaging said cam.

4. Apparatus according to claim 1 wherein said bending means comprises a forming member rotatable on an axis parallel to said marginal edge of said workpiece and engageable against said marginal edge.

5. Apparatus according to claim 4 wherein said forming member is secured to an elongated member extending parallel to the marginal edge of said workpiece and having gear teeth for rotation of said member on said parallel axis.

6. Apparatus according to claim 5 including drive means engaging said gear teeth for rotating said forming member.

7. Apparatus according to claim 6 wherein said drive means comprises a power source, a rotatable crankshaft operatively connected to said power source and gear means on said crankshaft having driving connection with said gear teeth on said forming member. 

1. Apparatus for forming a reverse bend along an edge of a sheet of metal comprising: a frame, a pressure foot mounted on said frame and having a lip formation along an edge thereof, a stationary clamping member mounted on said frame above said pressure foot, means for raising said pressure foot for clamping a workpiece between said clamping member and said pressure foot with the marginal edge of said workpiece protruding beyond said clamping member and said pressure foot, means engageable with said marginal edge of said workpiece for reversely bending said marginal edge about said lip formation, means for withdrawing said pressure foot from said workpiece to disengage said lip formation from said workpiece while said bending means is maintained engaged with said marginal edge for continued bending thereof, means operable subsequent to said disengagement for continuing the movement of said bending means to continue reverse bending to the degree required to compensate for springback and produce a final reverse bend of the required degree.
 2. Apparatus according to claim 1 wherein said means for raising said pressure foot comprises a rotatable shaft, a cam mounted on said shaft, a rocker arm connected at one end to said pressure foot and having a cam follower engageable with said cam, the other end of said rocker arm being pivotally mounted on said frame.
 3. Apparatus according to claim 1 wherein said means for withdrawing said pressure foot from said workpiece comprises a rotatable shaft, a cam mounted on said shaft, a bracket connected to said pressure foot and having a cam follower engaging said cam.
 4. Apparatus according to claim 1 wherein said bending means comprises a forming member rotatable on an axis parallel to said marginal edge of said workpiece and engageable against said marginal edge.
 5. Apparatus according to claim 4 wherein said forming member is secured to an elongated member extending parallel to the marginal edge of said workpiece and having gear teeth for rotation of said member on said parallel axis.
 6. Apparatus according to claim 5 including drive means engaging said gear teeth for rotating said forming member.
 7. Apparatus according to claim 6 wherein said drive means comprises a power source, a rotatable crankshaft operatively connected to said power source and gear means on said crankshaft having driving connection with said gear teeth on said forming member. 